Title Blocks and Lettering
By: John yank
Sheet Layout: U.S. Customary
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Table 4-1 gives specific sizes for standard sheets. For example, an A-size sheet
placed in the horizontal position is 8.50 vertically and 11.00 horizontally (8.50
11.00). When placed in the vertical position, it is 11.00 vertically
and 8.50 horizontally (11.00 8.50). B- and C-size sheets are generally not used
in the vertical position.
Figure 4-3 shows a recommended layout for the title block, which should
be placed in the lower right-hand corner of the drawing. Since it is only
recommended, it can be altered in both size and content. For example, “cage code” is
a reference number generally used on drawings prepared for government contracts.
It can be eliminated on drawings that are not government-related. Since the trim
sizes recommended by ASME and ISO are in almost universal use in industry, they
are also useful sizes for drafting courses. Most of the drawing problems throughout
this book are planned for A-, B-, A4-, or A3-size sheets. However, to reduce
the amount of time and space required to draw the title blocks, you may use the
modified version shown in Figure 4-4 for U.S. Customary drawings. Alternate layouts
are shown in Figure 4-5. Your instructor may assign one of these or one that he or
she has designed.
Sheet Layout: metric
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In Table 4-1, you will see that the smallest metric-size sheet is
A4. Placed in a horizontal position, it is 210 mm vertically and
297 mm horizontally (210 297). When placed in a vertical position,
it is 297 mm vertically and 210 mm horizontally (297 210). The A4size sheet may be used in either position.
Larger sheets are generally used only in the horizontal position.
Figure 4-6 shows a recommended layout for the metric title block. It
is essentially the same as the decimal-inch title block. The difference
is in the units of measure used to lay it out. Like
the U.S. Customary recommendations, metric recommendations
may be altered to accommodate the user’s specific
requirements. Figures 4-7 and 4-8 show recommended A4 and A3
drawing-sheet layouts with borders and title blocks. These have
been modified from the recommended ISO standard metric sheet
Working with Layers
• All CAD programs, including AutoCAD, have a system of layers that
gives the CAD operator much greater control over a drawing. A layer
is similar to a transparent paper overlay. By setting up a layer for
dimensions, for example, the CAD operator can control whether
dimensions are displayed by turning the layer on and off, or by
“freezing” and “thawing” it, as shown in Figure 4-10. Most
companies have rules about what layers
to use, what to call them, and what colors Table 4-2
Drawing limits should be associated with them. Some
companies even use their own drawing templates in which these
layers have already been set up. For instructional purposes, this
textbook will use a generic set of layers. These layers are
shown in Table 4-3.
Creating a New Layer
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To set up new layers in a drawing, enter the LAYER command. Look closely at the contents of the dialog box. The 0 layer is the
default layer. Notice that several properties are listed
for each layer, including:
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layer name
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on or off
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frozen or thawed
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layer color
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linetype
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line weight
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plot style
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plot (whether the layer plots when the drawing is printed)
Some versions of AutoCAD have additional properties, but those listed here are common to all versions. One of the standard layers
used in this textbook is the Objects layer. This layer will be used for all of the visible lines of the part or object. Therefore, you already
know that it will need to be a solid
(or continuous) line that is .30 mm thick. To create a new layer named Objects, click the New button in the dialog box. A new
layer appears in the window, and the layer name is highlighted. Type the word Objects in the layer name box.
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Setting the Layer Color
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By default, new layers in AutoCAD are white. To set the color for
a layer, pick White or the color box for that layer. A color
palette appears. To choose a different color, just pick a color and
pick OK. However, because this is the Objects layer, leave it
white. Colors are used in CAD programs to help the CAD operator
distinguish among the layers. See Figure 4-11. Some
companies prefer to use white for all of their layers. Others establish
company-wide standards. For example, they may declare that all
electrical wiring will be on a blue layer named Electr. These colors
may or may not print, depending on the plot setting and the printer
being used. It is also possible to set up the layers in various colors,
but set up a plot style to print them all in black ink. Therefore, the
color of a layer may or may not determine the color of the lines on
that layer when the drawing is
printed. This is up to the individual drafter or company.
Selecting the Line Type
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AutoCAD gives new layers a continuous linetype by default, so
the Objects layer is already set up for the correct linetype.
However, as you can see in Table 4-3, you will need to change it for
some of the other layers. To do so, click the word Continuous.
A dialog box appears from which you can change the linetype, but
notice that you have no other choices. To load other standard
linetypes into the drawing, pick the Load button. Another dialog
box appears, allowing you to select from several ISO and ASME
linetypes. To load the ISO standard dashed line, for example,
choose ISO02W100 ISO Dash and pick OK. The linetype
becomes available for use in the drawing. To choose the ASME
standard dashed line for hidden lines, scroll down to Hidden,
pick it, and pick OK.
Finishing Layer Setup
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Now finish the layer setup for your drawing by
creating the other layers listed in Table 4-3. Be
sure to give each layer the properties shown in
the table. Then enter the Save command
to save the drawing fi le. Because of the settings
chosen in this example, a suitable name for this
file in Chapter 4 ASME B Full
Scale, or use a name given by your instructor.
Selecting the Line Width
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The default line width in AutoCAD is 0. This does not
mean that the line does not print. However, the width of
the line is not
defined. You can and should define the width of the lines
on your drawings. To do so, pick the word Default in the
Line Width column for the Objects layer. AutoCAD
specifies all of its line widths in millimeters, as shown in
Figure 4-12. Visible lines in CAD are generally made at
a width of .12 , or .30 mm. Select .30 mm from the list of
line widths, and pick OK to apply it to the
Objects layer.
Setting the Text Style
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The default text style in AutoCAD is the Standard style. This style is boxy and does
not look much like hand-lettered text. Therefore, drafters generally use the Roman
Simplex font
for mechanical drawings. Follow these steps to set the text of a drawing to Roman
Simplex.
1. Start AutoCAD by double-clicking the AutoCAD icon on your screen, and open a
new drawing fi le by selecting New...
from the File menu. What happens next varies depending on your version of
AutoCAD. In most versions, you can choose to
start a drawing from scratch. If AutoCAD prompts you for a template file,
choose acad.dwt and press Enter or OK.
2. Enter the STYLE command and press the New... button in the dialog box.
3. Type in a name for the new style, choosing a name (such as “Roman”) that will
help you remember what font the style uses.
4. Pick the down arrow under Font Name and select romans.shx to activate
the Roman Simplex font.
5. Pick the Apply button and then the Close button.
The Roman Simplex style is now activated in the current drawing and is set as the
current default.
Composition
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In lettering, composition means arranging words and lines with
letters of the right style and size. Letters in words are not placed
at equal distances from each other. They are placed so that the
spaces between the letters look equal. The distance between
words, called word spacing, should be about equal to
the height of the letters. Figure 2-47 shows examples of proper and
improper letter and word spacing.
Tools such as lettering triangles and the Ames lettering instrument
are available to help create neat, uniform lettering with
the proper spacing. See Figure 2-48. On mechanical drawings,
drafters create ruled guidelines spaced .12" (3.5 mm) apart to
help keep their lettering uniform. When you are sketching, however,
you will estimate the appropriate distances.